Control of inlet flow to centrifugal fluid movers



Oct. 11, 1966 w TE ETAL 3,278,115

CONTROL OF INLET FLOW TO CENTRIFUGAL FLUID MOVERS Filed April 23, 1965 INVENTORS Douglas F. White Y Gunner Heskesfud ATTORN EY United States Patent 3,278,115 CONTROL OF INLET FLOW T0 CENTRIFUGAL FLUID MOVERS Douglas F White, Bedminster, and Gunnar Heskestad, East Brunswick, N..l., assignors to American Radiator & Standard Sanitary Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 23, 1965, Ser. No. 450,360 6 Claims. (Cl. 230-127) This invention pertains to centrifugal fluid movers and more particularly to the control of the flow of fluid into centrifugal fans or blowers.

Centrifugal fluid movers such as fans or blowers axially take in fluid which is radially propelled outward and circumferentially driven to a tangential outlet for expulsion therefrom. The first portion of travel requires an abrupt change in directions from an axial flow to a radial flow.

Presently constructed inlets of centrifugal fluid movers do not permit such an abrupt change. Therefore, the actual working surface of the fluid driving means such as blades is inefficiently utilized. In particular, when a typical centrifugal fluid mover employs a rotor which drives a plurality of blades to revolve about an axis, the inlet geometry is such that there is a non-uniform flow of fluid along the length of the blades. In fact, the entering fluid receives very little guidance and as a result portions of the blades near the inlet receive very little flow and consequently do very little work on the flow.

It is accordingly a general object of the invention to improve the efliciency of centrifugal fluid movers.

It is another object of the invention to direct the inlet flow of fluid in a centrifugal fluid mover so that a greater portion of the fluid driving blades do work on the flowing fluid.

It is a further object of the invention to more uniformly distribute the inlet flow of fluid over the entire length of the blades of a centrifugal fluid mover.

It is yet another object of the invention to provide an improved centrifugal fluid mover for satisfying the above objects.

Briefly, the invention generally contemplates a centrifugal type fluid mover which has a fluid inlet with a peripheral edge adjacent a plurality of blades. The blades extend in a direction axially from the inlet and are revolvable about the axis of the inlet. The fluid passing through the inlet is directed toward the blades by applying suction to the fluid moving over the peripheral edge of the inlet.

A feature of the invention is concerned with utilizing portions of the fluid mover and the moving fluid itself to obtain the required suction.

Other objects, features and advantages of the invention will be apparent from the following detailed description, when read with the accompanying drawing, which shows a prior art centrifugal fluid mover and, by way of example and not limitation, a centrifugal fluid mover utilizing the invention.

In the drawing:

FIG. 1 is a radial sectional view of a prior art centrifugal blower of the Sirocco type;

FIG. 2 is a side elevation of a Sirocco type centrifugal blower in accordance with the invention; and

FIG. 3 is a sectional view taken along the line 33 of FIG. 2.

Referring to FIG. 1, the conventional Sirocco type centrifugal blower includes the rotor 12 within the scroll housing 14. Rotor 12 includes the support 16 from which axially extend blades 18. Fixed to rotor 12 is shaft 20 passing through housing 14 and bearing 22 for coupling to a rotary source of power (not shown).

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Each blade 18 has an inlet edge 18A, and outlet edge 18B and an end 18C. The ends 18C of the blades I18 are adjacent the axial inlet 24 of housing 14. The portion 14A of housing 14 is contoured to facilitate smooth entry of fluid represented by stream lines designated by reference numerals 26 and 28.

When rotor 12 is rotating, fluid such as air is drawn into the central region of rotor 12 through the axial inlet 24 and gradually moves radially toward the inlet edges 18A of blades 18. The fluid when it reaches the regions of blades 18 is given a circumferential component of acceleration by the rotating blades and eventually driven from a tangential outlet (not shown) in housing 14.

It has been found because of the inlet geometry very little, if any, of the fluid comes into contact with the portions of the blades 18 to the left of streamline 26, as depicted in FIG. 1. In other words, the inlet fluid stream is not uniformly distributed along the inlet edges 18A of blades 18. In fact, the portions of the blades 18 immediately adjacent axial inlet 24 perform substantially no work on the inlet fluid flow.

In order to obtain more work from the blades, it is necessary to provide a more uniform distribution of inlet fluid along the blades. This can 'be accomplished by actively diverting the axially entering inlet fluid flow radially toward the blades. Such active diversion is obtained by the Sirocco type centrifugal blower 30 shown in FIGS. 2 and 3. Blower 30 includes the scroll housing 32 with an axial inlet 34 and a tangential outlet 36. Housing 32 includes a cylindrical portion 37 and a side portion 38. Side portion 38 has an axially inward extending portion 40 and a portion 42 extending radially outward therefrom. Portion 42 may be rolled axially outward to contact the inner surface of side portion 38 to provide an annular chamber 43. The junction of portions 40 and 42, which is the inner peripheral edge of axial inlet 34, is provided with a peripheral slot 41 that communicates with annular chamber 43.

Within housing 32 is rotor 44 comprising a support 46 from which blades 48 axially extend toward axial inlet 34. Support 46 is connected to shaft 50 which extends through housing 32 and is supported by bearing 52 for coupling to a rotary source of power (not shown).

Each of the blades 48 includes an inlet edge 48A and outlet edge 48B and an inlet end 48C. It should be noted that the inlet edges 48A are at a greater radial distance from the axis of rotation of the rotor than the inner peripheral edge of the axial inlet 34.

If nothing further were added to blower 30, then upon rotation of rotor 44, fluid would pass via axial inlet 34 to the central region of rotor 44 and gradually radially move toward the inlet edges 48A of blades 48. Blades 48 would impart a tangential acceleration to the fluid stream which moves into the region between the outlet edges 48B and the cylindrical portion 37 of housing 32.. The fluid stream would rotationally move in this region until reaching tangential outlet 36 from which it would be ex elled with a high tangential velocity.

It should be noted that because of the radial orientation of the peripheral edge of the axial inlet 34 and the inlet edges 48A of blades 48, fluid distribution along the blades would be at best no better than with the blower 10 of FIG. 1. However, it has been found that by applying suction to the fluid flowing past the edge of a conduit discontinuity, the fluid flow can be diverted or bent around the discontinuity. The peripheral edge of axial inlet 34 in the junction or portions 40 and 42 of housing 32 is such a discontinuity. Therefore, when suction is applied to the peripheral edge through the agency of peripheral slot 41 the fluid represented by streamlines 54, 56 and 58 is actively deflected radially outward toward blades 48. In fact, as is apparent from streamline 54,

3 the fluid even contacts the inlet ends 48C of the blades. It has been found that a slot width which is greater than one one-hundredths of the inlet diameter, and a slot angle of from 30-90 degrees worked very well.

Although an external source of suction may be coupled to annular chamber 43, the suction is preferably obtained from the blower itself. Accordingly, outlet 60 is provided in the casing or housing just below the outlet 36 as illustrated in FIG. 2. The pressure inside the housing at outlet port 60 downstream of tangential outlet 36 is normally quite low, and therefore, can be used to provide adequate suction flow. Conduit 62 connects outlet port 60 to an opening 61 in side portion 38 of housing 32 which communicated with the annular chamber 43.

There has thus been shown a method of improving the efliciency of centrifugal type blowers by applying suction to the peripheral edge of the axial inlet to actively deflect the inlet fluid flow toward the rotor blades. The deflection is of such an extent that fluid flow is more uniformly distributed along the blades so that substantially the entire surface of each of the blades can do work on the fluid.

In addition there has been shown an improved centrifugal blower which obtains the required suction by utilizing an outlet tapped into the output fluid stream of the blower.

While only one embodiment of the invention has been shown and described in detail, there will now be obvious to those skilled in the art many modifications and variations which satisfy many or all of the objects and to which accrues the advantages of the invention. However, such modifications and variations will come within the spirit of the invention as defined by the appended claims.

What is claimed is:

1. A centrifugal mover of homogeneous fluid comprising: a plurality of blades, each of said blades including at least one end and support means for supporting said blades parallel to and radially displaced from an axis, means for rotating said support means about said axis, a scroll housing disposed about said support means and said blades, said scroll housing being provided with an axial inlet opposite one end of each of said blades, said inlet having a peripheral edge adjacent said one end of each of said blades, and means for applying suction along said peripheral edge for diverting fluid passing said peripheral edge onto said one end of said blades.

2. A centrifugal gas mover comprising a plurality of blades, each of said blades including at least an inlet end portion, and inlet and outlet edge portions; support means for supporting said blades parallel to and radially displaced from an axis; the inlet edge portion of each of said blades being closer to said axis than the outlet edge portion of each of said blades; means for rotating said support means so that said blades revolve about said axis; a scroll housing disposed about said support means and said blades, said scroll housing including a first portion opposite the outlet edge portions of said blades and a second portion opposite said inlet end portions of said blades, said second portion being provided with an inlet means including a peripheral edge adjacent both said inlet end portions and said inlet edge portions; and means for applying suction along said peripheral edge for diverting gas passing over said peripheral edge onto said first edge portions in the region of said inlet end portions of said blades.

3. A centrifugal gas mover comprising: a plurality of blades, each of said blades including at least an inlet end portion, an inlet and outlet edge portions; support means for supporting said blades parallel to and radially displaced from an axis; the inlet edge portion of each of said blades being closer to said axis than the outlet edge portion of each of said blades; means for rotating said support means so that said blades revolve about said axis wherein the extremities of said inlet end portions define a circle; a scroll housing disposed about said support means and said blades, said scroll housing including a first portion opposite the outlet edge portions of said blades and a second portion opposite said inlet end portions of said blades, said second portions being provided with an inlet comprising an axially inward extending portion and a portion extending from said axially inward extending portion radially inward and terminating in the region of said inlet end portions of said blades, the junction of said axially inward extending portion and said portion extending radially inward therefrom being provided with a peripheral slot adjacent said defined circle; and means for applying suction to said peripheral slot so that gas flowing over said peripheral slot is diverted radially onto the inlet edge portions of said blades.

4. A centrifugal gas mover comprising: a plurality of blades, each of said blades including at least an inlet end portion, and inlet and outlet edge portions; support means for supporting said blades parallel to and radially displaced from an axis; the inlet edge portion of each of said blades being closer to said axis than the outlet edge portion of each of said blades; means for rotating said support means so that said blades revolve about said axis wherein the extremities of said inlet end portions define a circle; a scroll housing disposed about said support means and said blades, said scroll housing including a first portion opposite the outlet edge portions of said blades and a second portion opposite said inlet end portions of said blades, said second portion being provided with an inlet comprising an axially inward extending portion and a portion extending from said axially inward extending portion radially inward and opposite the region of said inlet end portions of said blades, the junction of said axially inward extending portion and said portion extending radially inward therefrom being provided with a peripheral slot opposite said so defined circle, an annular chamber means including at least said axially inward extending portion and said portion extending radially inward therefrom; and means for applying suction to said annular chamber means so that gas passing over said peripheral slot is diverted radially toward the inlet edge portions in the region of said inlet end portions of said blades.

5. The centrifugal mover of claim 1 wherein said suction applying means includes a conduit means connecting said peripheral edge to a low pressure region within said scroll housing.

6. The centrifugal mover of claim 4 wherein said suction applying means includes a conduit means connecting said annular chamber means to a low pressure region within said scroll housing.

References Cited by the Examiner UNITED STATES PATENTS 1,345,638 7/1920 Schmidt 230127 1,845,152 2/1932 Hutchinson 230-127 1,875,881 9/1932 Morse 230-127 2,552,264 5/1951 Edwards 103113 2,581,828 1/1952 Adams 103113 2,780,999 2/1957 Compton et al. l03-113 FOREIGN PATENTS 673,662 3/1939 Germany.

MARTIN P. SCHWADRON, Primary Examiner. HENRY F. RADUAZO, Examiner, 

1. A CENTRIFUGAL MOVER OF HOMOGENEOUS FLUID COMPRISING: A PLURALITY OF BLADES, EACH OF SAID BLADES INCLUDING AT LEAST ONE END OF SUPPORT MEANS FOR SUPPORTING SAID BLADES PARALLEL TO AND RADIALLY DISPLACED FROM AN AXIS, MEANS FOR ROTATING SAID SUPPORT MEANS ABOUT SAID AXIS, A SCROLL HOUSING DISPOSED ABOUT SAID SUPPORT MEANS AND SAID BLADES, SAID SCROLL HOUSING BEING PROVIDED WITH AN AXIAL INLET OPPOSITE ONE END OF EACH OF SAID BLADES, SAID INLET HAVING A PERIPHERAL EDGE ADJACENT SAID ONE END OF EACH OF SAID BLADES, AND MEANS FOR APPLYING SUCTION ALONG SAID PERIPHERAL EDGE FOR DIVERTING FLUID PASSING SAID PERIPHERAL EDGE ONTO SAID ONE END OF SAID BLADES. 